#include <iostream>
#include <cmath>
#include <algorithm>
#include <cstring>
#include <vector>
#include <map>
#include <queue>
#include <cstdio>
#include <string>
#include <stack>
#include <set>
#define IOS ios::sync_with_stdio(false), cin.tie(0)
using namespace std;
typedef long long ll;
priority_queue<double,vector<double>,less<double> > q;
int main()
{
    IOS;
    ll n;
    cin>>n;
    double num;
    for(ll i=0;i<n;i++){
        cin>>num;
        q.push(num);
    }
    double ans=0,temp;
    for(ll i=1;i<n;i++){
        double x=q.top();
        q.pop();
        double y=q.top();
        q.pop();
        temp=2*sqrt(x*y);
        q.push(temp);
    }
    ans=q.top();
    printf("%.3f\n",ans);
    getchar();
    getchar();
    return 0;
}
